1,240 articles
Otolith
Otolith (otoconia): calcium carbonate crystals in the utricle and saccule of the inner ear's vestibular system, detecting linear acceleration and head tilt relative to gravity; distinct from semicircular canals, tested clinically by VEMP, vOCR, and SVV.
Otorrhagia
Otorrhagia (otorragia) is the medical term for bleeding from the ear, ICD-10 H92.2 and ICD-11 AB70.1, distinct from otorrhea and hemotympanum, caused by eardrum perforation, infection, trauma, or tumor.
Otorrhoea
Otorrhoea (otorrhea) is ear discharge, usually from otitis media, otitis externa, or a perforated eardrum; types include purulent, serous, bloody, mucoid, and clear, with CSF leak after head trauma a serious cause.
Otosclerosis
Otosclerosis: abnormal bone remodeling fixing the stapes in the middle ear, causing progressive conductive hearing loss, tinnitus, and sometimes vertigo; treated with hearing aids or stapes surgery (stapedectomy, stapedotomy).
Ototoxicity
Ototoxicity is drug- or chemical-induced inner ear damage causing hearing or balance loss, chiefly from aminoglycoside antibiotics and platinum chemotherapy such as cisplatin, with pooled prevalence near 43%.
OWBLM trial
OWBLM (NCT04425681) is a phase II single-arm trial of osimertinib 80 mg daily plus bevacizumab 7.5 mg/kg for leptomeningeal metastasis from EGFR-mutant NSCLC; 14 patients, median LM PFS 9.3 months, ORR 50%, LM OS 12.6 months.
Pacemaker neuron
A pacemaker neuron is a neuron that generates rhythmic bursts of action potentials independently of synaptic input, driving circadian rhythms in the suprachiasmatic nucleus and respiration in the preBötzinger complex.
Pain Threshold
Pain threshold: the minimum stimulus intensity perceived as painful (IASP definition); distinct from pain tolerance. Measured psychophysically via QST methods of limits or levels, with pressure, thermal, and electrical stimuli; reliability varies by modality.
Palinopsia
Palinopsia, or visual perseveration, is the abnormal persistence or recurrence of an image after its stimulus is gone. Distinct from normal afterimages, it divides into hallucinatory (lesions, seizures) and illusory (migraine, drugs) types.
Pantothenate kinase-associated neurodegeneration
PKAN (pantothenate kinase-associated neurodegeneration, formerly Hallervorden-Spatz syndrome, NBIA1) is a rare autosomal recessive PANK2 disorder causing dystonia, brain iron accumulation, and the eye-of-the-tiger MRI sign.
Papilledema
Papilledema is optic disc swelling caused by elevated intracranial pressure, usually bilateral. Most common cause is idiopathic intracranial hypertension; diagnosed with MRI/MRV, lumbar puncture, and OCT; treated with acetazolamide, weight loss, or shunting.
Paraneoplastic cerebellar degeneration
Paraneoplastic cerebellar degeneration (PCD), or paraneoplastic cerebellar ataxia, is tumor-induced autoimmune Purkinje cell loss causing subacute ataxia, mainly anti-Yo antibody with breast and gynecologic cancers, with poor prognosis.
Paraplegia
Paraplegia is paralysis of the lower body and both legs with preserved arm function, usually from spinal cord injury below the neck; also called paraplegic paralysis, distinct from quadriplegia or tetraplegia.
Parasympathetic nervous system
Parasympathetic nervous system, the craniosacral division of the autonomic nervous system coined by Langley. Outflow via cranial nerves III, VII, IX, X and S2–S4; long preganglionic fibers, acetylcholine, ganglia near target organs, rest-and-digest function.
Parasympathetic neuron
Parasympathetic neuron: cholinergic motor neuron of the parasympathetic (craniosacral) autonomic division; preganglionic cells in brainstem nuclei and S2–S4, postganglionic cells in ganglia near target organs, vagus carrying 75% of fibers.
Parietal lobe
The parietal lobe, bounded by the central and parieto-occipital sulci, contains primary somatosensory cortex and posterior association areas for spatial attention, reaching, language, and number; damage causes neglect, apraxia, Gerstmann and Bálint syndromes.
Parinaud's syndrome
Parinaud's syndrome, also called dorsal midbrain or Sylvian aqueduct syndrome, is a neuro-ophthalmologic disorder caused by dorsal midbrain lesions, classically pineal tumors, producing upward gaze palsy and convergence-retraction nystagmus.
Parkinson's disease
Parkinson's disease, also called shaking palsy, is the second-most common neurodegenerative disorder, defined by substantia nigra dopaminergic neuron loss and α-synuclein Lewy bodies, causing tremor, rigidity, and bradykinesia, treated with levodopa and deep brain stimulation.
Parkinsonism
Parkinsonism, also called parkinsonian syndrome or Parkinson-plus when atypical, is a clinical syndrome of bradykinesia with rigidity, resting tremor, or postural instability; Parkinson's disease is its most common cause.
Patch-sequencing
Patch-seq (Patch-sequencing) is a multimodal neuroscience technique combining patch-clamp electrophysiology, single-cell RNA sequencing, and morphology in the same neuron, first implemented reliably in 2016 and central to brain cell type atlases.
Patellar reflex
Patellar reflex (knee jerk, Patellarsehnenreflex): monosynaptic L2-L4 stretch reflex elicited by tapping the patellar tendon, causing quadriceps contraction; described by Erb and Westphal in 1875 and increasingly quantified with EMG and motion analysis.
Patulous Eustachian tube
Patulous Eustachian tube (tuba aperta, ICD-10 H69.0): an abnormally open Eustachian tube causing autophony and eardrum movement with breathing; linked to weight loss, treated by plug or shim surgery.
Pellucid marginal degeneration
Pellucid marginal degeneration, also called pellucid marginal corneal degeneration (PMCD), is a rare, usually bilateral disorder in which a crescent-shaped band of the peripheral cornea thins progressively.
Pelvic splanchnic nerves
Pelvic splanchnic nerves (nervi erigentes) are preganglionic parasympathetic nerves from S2-S4 anterior rami supplying the bladder, hindgut, ureter, prostate, urethra, and erectile tissue via the inferior hypogastric plexus.
Peptidergic neuron
Peptidergic neuron (Cell Ontology CL:0000110): a neuron using neuropeptides as transmitters, stored in large dense-core vesicles, acting on GPCRs, usually co-released with classical transmitters.
Perception
Perception is the process by which the nervous system computes over sensory inputs to build models of the world, from receptor transduction through multisensory integration and predictive inference.
Perfluorohexyloctane
Perfluorohexyloctane (F6H8) is a chemically inert semifluorinated alkane used in prescription eye drops for dry eye disease, marketed as MIEBO in the United States since 2023.
Perforated eardrum
Perforated eardrum (tympanic membrane perforation): a hole or tear in the eardrum from infection, injury, loud noise, or pressure change; usually heals within weeks to two months, with myringoplasty for persistent holes.
Perichondritis of external ear
Perichondritis of external ear (ICD-11 AA04; ICD-10 H61.0) is infection of the perichondrium around outer-ear cartilage, usually after cartilage piercing or trauma, most often caused by Pseudomonas aeruginosa, risking cauliflower ear.
Perifoveal exudative vascular anomalous complex
Perifoveal exudative vascular anomalous complex (PEVAC, also PVAC) is a rare idiopathic large aneurysmal lesion of the deep retinal capillary plexus near the fovea, diagnosed by exclusion, poorly responsive to anti-VEGF, distinct from type 3 MNV and MacTel.